(1) Field of the Invention
One possible embodiment of the present disclosure relates, generally, to double block and bleed valves. Specifically, one possible non-limiting embodiment of the present disclosure relates to an expanding dual disc gate valve providing substantially frictionless movement during operation.
(2) Description of the Background
Double block and bleed valves are commonly used in applications requiring simultaneous blocking of both upstream and downstream flow. Conventional systems for double block and bleed valves require the use of two valves and a center spool piece inserted between the two valves. A bleed valve is then fitted in this center spool piece to drain any hydrocarbons and/or pressure from the spool piece, providing verification of seat and seal integrity of the respective valves.
These valves are effective in multiple applications including off-shore platforms, aviation fueling, tank farms, terminals, custody transfer units, meter stations, multi-product manifolds, bulk product isolation, and the like.
Seal abrasion is an inherent problem in the design of these valves, whether the design implements a ball valve or a gate valve. The seating segments become scored as the ball and/or gate make metal to metal contact with the valve body when cycling between the open and closed positions, and/or wedged into the sealing position. After time, foreign particles become lodged between the seat of the ball or gate further scoring the seating surfaces, and ultimately result in valve leakage.
Corrosion of the plug is another common issue associated with double block and bleed valves, contributing to seizing slips, damaged seals, and peeling and/or cracking of the electro nickel plated seats. Furthermore, maintenance and repair of conventional double block and bleed valves are both costly and time consuming, in addition to being too bulky for compact applications.
A need exists for a valve system that is resistant to the seal abrasion and corrosion problems. A need also exists for inline repairable/replaceable seals should maintenance be required for the internal valve components. Those of skill in the art will appreciate the present system which addresses the above and other problems.